This invention relates to layered integrated circuit assemblies and more specifically to fabrication of metal posts by laser assisted chemical vapor deposition, for utilization as electrical and/or mechanical interconnections therein.
Interconnecting the integrated circuitry on a plurality of wafers has progressed from the use of motherboards and/or cables, to stacking the wafers in layered assemblies wherein a plurality of permanent metal interconnections and made between aligned locations on the wafers. Although most such interconnections are intended for passing electrical signals, mechanical purposes are also known therefor.
Various metalization systems or techniques, including the use of non-configured metal bumps are known in the prior art for providing such interconnections, with the most popular at the present time being the use of solder bumps. All such prior art techniques involve the time consuming use of masks, such as for the application of photoresist, and/or result in rather low density populations of the interconnections and therefore, fail to provide the high number of input and output terminals that are required for today's complex circuitry. Furthermore, the interconnections which result from some prior art techniques have little structural integrity under temperature cycling conditions.